In MTG, what booster packs contain the planeswalkers?

Lorwyn, Shards of alara, Conflux, M10, zendikar, worldwake, rise of eldrazi, and M11 all have planeswalkers in them, although if you want planeswalkers really bad, like extra-super-bad, planeswalker duel decks are the way to go. Decks like Garruk vs lilliana have Garruk and Lilliana, and a decent 59 other cards, as the same a Jace vs chandra, but Elspeth vs tezzeret is probably your best bet. If you still want walkers, go for lorwyn, where there's also commands and they're only rare, not mythic.